Troubleshooting of High Performance Liquid Chromatography (HPLC)
There are many test instruments used in the laboratory, and high-performance liquid chromatography (HPLC) is one of them. The instrument is based on classical chromatography, citing the theory of gas chromatography, and technically it changes the traditional mobile phase to high-pressure delivery. This article will give you the brief introduction of the chromatography, characteristics, failure causes, and treatment methods of high-performance liquid chromatography (HPLC).
Introduction of High-performance Liquid Chromatography
High performance liquid chromatograph (HPLC) is an instrument based on the principle of high performance liquid chromatography, which is mainly used to analyze less-volatile and thermal-unstable organic compounds with high boiling point and large molecular weight. It consists of solvent bottles, pump, sample injector, chromatographic column, detector, recorder and workstation.
How does high performance liquid chromatography work?
The mobile phase in the reservoir is pumped into the system by a high-pressure pump, and the sample solution passes through a sample injector then enters the mobile phase, which loads the sample solution into a chromatographic column (stationary phase). Because the various components in the sample solution have different distribution coefficients in the two phases, when they are moving relatively in the two phases, after repeated adsorption-desorption distribution processes, the moving speed of each component is greatly different, and the components are separated into single components flowing out of the column in turn. When passing through the detector, the sample concentration is converted into electrical signal and transmitted to the recorder, and the data is printed out in the form of chromatogram.
Applications of High-Performance Liquid Chromatography
HPLC is widely used in food, pharmaceutical, environment, agriculture and scientific research
1. Application in environmental analysis:
It can be used for the analysis of cyclic aromatic hydrocarbons (PAHs), pesticide residues, etc.
2. Application in food analysis:
It can be used for food nutrition analysis, food additive analysis, food contaminant analysis, etc.
3. Application in life science:
Purification, separation, and determination of molecular weight substances in life science, genetic engineering, clinical chemistry, molecular biology, and biochemistry can be studied at the molecular level.
4. Application in the medical examination: analysis and determination of metabolites in body fluids, pharmacokinetics, clinical drug monitoring, etc.
5. Application in inorganic analysis: analysis of anions and cations, etc.
Common Faults and Treatment Methods of High-Performance Liquid Chromatography
| Fault Description | Cause Analysis | Solution |
|
Front panel status indicator does not light up |
Cable connection failure | Open the chassis and reconnect reliably |
| Switching power supply module cannot work and supply power | Replace the switching power module | |
| Signal intensity too low | Bubbles are generated in the flow cell | Flush the flow cell and degasify the mobile phase |
|
Prompt deuterium lamp failure |
Deuterium lamp cannot be lit | Restart the instrument. If the fault cannot be eliminated, please replace the deuterium lamp. |
Common troubleshooting of autosampler
| Fault Description | Cause Analysis | Solution |
| Abnormal electrical initialization of the instrument | Software prompts: The zero-point optocoupler of the horizontal motor fails. |
1. Restart the instrument 2. Check the sample chamber for any obstacles 3. Check the sensor at the corresponding position for any obvious abnormal phenomena such as looseness and line breakage 4. Call the after-sale service to solve the problem |
| Software prompts: The zero-point optocoupler of the vertical motor fails. | ||
| Software prompts: The zero-point optocoupler of the tray motor fails. | ||
| Software prompts: The zero-point optocoupler of the syringe motor fails. | ||
| Software prompts: EEPROM is unable to read or write. |
1. Restart the instrument 2. Call the after-sale service to solve the problem |
|
| The software for the injection process indicated an exception | Software prompts: Sample vial is missing |
1. Check whether the sample vial position is consistent with the software setting position 2. Restart the instrument 3. Call the after-sale service to solve the problem |
| Software prompts: The door is open |
1. Check whether the door is normally closed 2. Check the door sensor for abnormalities 3. Restart the instrument 4. Call the after-sale service to solve the problem |
|
| Line fault | The status light on the front panel is not on |
1. Restart the instrument 2. Check whether the power cord is reliably connected 3. Check whether the power switch is on 4. Check the fuse for damage 5. Call the after-sale service to solve the problem |
| The autosampler does not trigger the chromatogram |
1. Check whether the trigger line is reliably connected 2. Check whether the instrument serial line is connected reliably 3. Check whether the software instrument networking light is flashing |
|
| Fluid line fault | There are obvious bubbles in the syringe during injection |
1. Perform flushing fluid line process 2. Check whether the pipe joints are loose 3. Check joints for leakage 4. Too little liquid in the sample vial |
| There are small bubbles in the fluid line during injection | ||
| Poor reproducibility of sample injection |
1. No ultrasonic processing to the sample 2. No ultrasonic processing to the wash solvent 3. There are obvious air bubbles in the pipeline syringe during injection 4. The sample vial was reused without cleaning |
Common troubleshooting of pump
| Fault Description | Cause Analysis | Solution |
| If the front panel status indicator is not light, | the connection may be loose, | Open the shell, and reconnect reliably. |
| Detection of power supply module | Replacement power supply module | |
| Pump pressure is 0 | pump head with air | Open purge valve, with syringe pumping, until there is liquid from the empty valve flow, and then tighten the valve. |
| Pressure alarm | pressure limit range setting unreasonable | According to the actual test needs, set a reasonable pressure limit range. |
| Pipeline blockage leads to excessive pressure. | Check whether the pipeline is gambling after pump head. | |
| Leakage causes too little pressure | Check whether there is any damage to all levels of pipelines and streets after the pump head. | |
| The buzzer keeps buzzing at a frequency of 0.5HZ. | Motor blocked, pressure upper limit alarm, pressure lower limit alarm, liquid leakage alarm. | Check and determine the cause of the error, and then solve it according to the situation |
| The buzzer beeps 3 times at a frequency of 1HZ and then stops | Leak sensor failure, pressure sensor failure, fan failure, photoelectric switch failure, solvent threshold alarm, unsuccessful initialization. | Check and determine the cause of the error, and then solve it according to the situation |